In man the respiratory mucous membranes will be investigated non-invasively with radio-aerosols to determine the effects of ambient pollutant, ozone, on airway mucociliary function. Repetitive exposure to 0.2 and 0.4 PPM ozone will be studied to determine if adaptation of mucus membrane function occurs, and whether the adaptation of airway function and subjective symptoms are causally related to the effects of ozone on mucociliary function. Smokers, with abnormal function, will be evaluated in longitudinal study to determine if mucociliary function, known to be depressed in these subjects while habituated to cigarettes, is influenced by ozone exposure; at follow-up, after 6 months of smoking cessation, mucociliary response to ozone exposure will be re-evaluated. Modification of ozone effects on mucous membrane physiology will be studied with lidocaine aerosol, to anesthetize airway receptors sensitive to ozone, and with ascorbic acid (orally), to reduce tissue mediators released during ozone inhalation. Lastly, the effect of ozone exposure on the deposition fraction of respired aerosol will be evaluated for 3 particle sizes, 2, 4 and 6 micron m diameters, representatives of coarse mode particulate pollution. These particles will be radiolabeled and thus will provide additional information on regional deposition within the lung. Our technique utilizes gamma camera imaging and chamber exposures to ozone. The information obtained will support our hypothesis that mucus membrane physiology is a primary determinant of the lung response to irritant stimuli, and better define the role of environmental pollutants in the induction or progression of airway abnormalities.